While hosting public Borderlands games, a few people have told me they’ve had trouble hosting games that other players could join.
I opened the following ports on my router and was able to host public games:
- 7777 (TCP, UDP)
- 27900 (UDP)
- 28900 (TCP)
- 28902 (TCP, UDP)
- 28910 (UDP)
Consult your router’s documentation for instructions on opening ports as methods will differ according to router manufacturer and interface.